The present invention relates generally to improved travelers and rings which are used in textile applications such as spinning rings and travelers for use on spinning frames and more particularly to a chemically deposited coating for travelers and rings providing both hardness and self-lubrication.
In conventional spinning and twisting operations, the limiting factor with respect to increased speeds has always been the wear force between the traveler and the ring. For example, as the textile industry moves to higher spinning speeds, traveler speeds also increase. Further, as spinning speeds increase, tension, the force exerted by the yarn on the traveler, and friction, the force which opposes relative motion between the yarn and the traveler and between the traveler and the ring, increase.
Collateral to the problems of wear resistance are those of lubricity. As the polished surfaces of the traveler wear, they become roughened, increasing the coefficient of friction between the traveler and the ring. Such increased friction results in heat build-up. It is not uncommon for the horns of travelers to burn off, which in addition to loss of production time for replacement of the traveler, can cause damage to the yarn and the ring.
Further, in addition to heat build-up, a roughened traveler will fray and eventually break the yarn, causing lost production time and a low quality end product. And such roughened travelers tend to become loaded with excess fibers resulting from such fraying, or fly, and again decrease production as they must be cleaned or replaced.
Typically, workers in the art have attempted to solve the aforesaid problems by either addressing the requirements of wear resistance or of lubrication. Such one-sided approaches to the present problems have enjoyed some limited success because wear resistance and lubricity are related. In a most general sense, as wear resistance, or hardness, increases such that surface roughening is less, the need for lubrication decreases. Conversely, as lubricity is increased, wear decreases.
U.S. Pat. No. 2,970,425 to Foard is one example of the conventional practice of electrically depositing a metal coating to a surface in order to increase hardness. Foard discloses electroplating spinning rings with a metallic coating having a leveling characteristic such that the outer surface of the coating material does not follow the contours of the surfaces of the ring but, rather, presents a smooth outer surface for traveler contact providing for an initially low coefficient of friction.
Such process, as well as others which provide for the coating by electro-deposition of rings and travelers, represent an improvement over the earlier prior art in that the metallic coating provides a hard surface which is comparatively resistant to wear and is initially smoother than non-coated surfaces. However, such coated surfaces are subject to chipping which raises the coefficient of friction and eventually leads to part failure. Further, such electro-deposited coatings are not deposited onto the part uniformly and produce an improperly balanced ring or traveler.
The problems of non-uniformity of metal coatings are addressed by electroless plating methods such as discussed in U.S. Pat. No. 3,226,924 to Dalpiaz which discloses a method of chemically depositing a metal onto a traveler which results in a uniform coating about the entire surface thereof. However, such chemically deposited metallic coatings also tend to chip.
Also of general interest is U.S. Pat. No. 2,448,150 to Mulholland which discloses providing a spinning ring with a metallic bearing insert. However, a metallic layer, whether applied electrically, chemically or physically, will not provide for as smooth a surface as such layer in combination with a lubricant.
Thus, it is generally known to introduce a lubricant such as oil or the like into a ring and traveler assembly. U.S. Pat. No. 3,304,710 to Kluttz discloses a spinning ring having a lubricant reservoir with means for conducting the lubricant onto the outer wearing surfaces of the ring. However, it is recognized that by such process of wicking oil from a reservoir, a mist of oil is created which produces stains and discolorations on the yarn, resulting in poor end product quality.
Further, oil splattered or spilled on the floor makes the work area unclean and unsafe. Moreover, fine particles of abraded metal from the traveler or ring combine with the lubricating oil and are oxidized thereby. When such oxidized particles contact the yarn, visible, difficult to remove, stains are produced.
In place of an oil-based lubricant, it has ,been known to apply a polymeric coating such as "Teflon".RTM. to travelers. However, such coating quickly wears off, leaving a bare surface subject to the wear discussed above. An alternative means for providing lubricity to metal ring assemblies is described in U.S. Pat. No. 3,084,501 to Kluttz which, while generally disclosing convoluted surfaces on rings which permit for the free passage of air between the ring and the traveler, refers to the method of impregnating an electropolished metal ring with sulphur to impart lubricity.
An alternative approach to the problems of lubricity has been to provide polymeric, rather than metallic, rings and travelers which inherently provide for a lower coefficient of friction. Plastic travelers have the added advantage of a light weight. It is generally acknowledged that as spinning rates increase, lighter travelers are required. Heretofore, it has been difficult to provide a light weight metal or metal coated traveler for high speed applications.
U.S. Pat. Nos. 3,387,447 to Trammell, et al. and 3,396,527 to Joseph, Jr. et al. disclose rings and travelers, respectively, molded from polyacetal resin which provides for a low coefficient of friction and is essentially self-lubricating such that external lubrication is not required. Both patents further disclose dispersing in the polyacetal resin, prior to molding, particulate fluorocarbon resin to further increase lubricity such that the end product ring or traveler has fluorocarbon particles dispersed throughout.
However, one problem with plastic parts is that they are poor conductors of heat with relatively low softening points. In the case of metal rings and travelers, the heat, which is developed as a result of the friction therebetween, is rapidly conducted away from the traveler. But because of the poor conductability of plastic, heat poses a much greater problem with respect to plastic parts. Trammell et al. address this problem by adding particles of conducting material such as bronze, copper or graphite to the plastic rings of that reference. However, it is generally known that such plastic parts, particularly plastic travelers, are only suitable for use with the heaviest yarns.
Thus, prior art attempts at providing rings and travelers for general spinning use which provide optimum wear resistance and lubricity have met with only limited success. Further, although attempts have been made, no prior art travelers are known which adequately meet the wear resistance and lubricity requirements of high speed spinning and twisting applications.